A modified alginate and/or modified pectin composition and method for preventing and/or treating diseases and/or conditions caused by circulating agents such as poisonous heavy metals, environmental toxins, calcium and cholesterol, is provided. The composition includes a modified alginate having a molecular weight of no more than 40,000 daltons and/or a modified pectin having a molecular weight of no more than 40,000 daltons. The method involves orally or intravenously administering the modified alginate and/or modified pectin composition, alone or with excipient.